The present invention relates in general to telephones, and, more particularly, to telephone security devices.
Unauthorized use of telephones includes the placing of long distance calls or other calls by one not authorized to place such calls. Furthermore, even if some limited use is authorized, it is possible for such authorized use to be exceeded.
Unauthorized use of the telephone results in losses to business, government, individuals and to the telephone company in all sections and regions of the country, and indeed, the world. Losses caused by unauthorized use of telephones are extremely large, and in some cases, such losses are measured in the millions of dollars per year.
While there are many devices for preventing unauthorized use of rotary dial-type telephones, such as, for example, that device shown in U.S. Pat. No. 2,469,806, there are no devices presently available for effectively preventing unauthorized use of the pushbutton-type telephone. The devices presently available either prevent any use to be made of a telephone by locking the receiver onto the telephone, or the like, or locking the rotary dial, or shorting out the telephone dial completely, or opening the circuit. Most of the presently available electronic rotary dial telephone locks involve some form of digit counter. Examples of digit counters used with rotary dial telephones are disclosed in U.S. Pat. Nos. 4,099,033, 3,786,196, 3,702,903, 3,727,007 and 4,063,036. For example, if long distance calls are to be prevented, a digit counter is associated with a rotary telephone set, and when the total number of digits exceeds a predetermined value, the telephone set is shorted out or open circuited, or otherwise prevented from completing the call.
Most of the presently available devices are quite complicated, expensive and difficult to install. An example of a complicated system which is installed at the switching equipment located at a central office is disclosed in U.S. Pat. No. 4,002,848. Furthermore, in many prior art devices, a user has little, if any, immediate control over the operation of such devices. To change the mode of operation, such user must contact the telephone company, and have a complex operation carried out. Such cost and difficulty are serious drawbacks to these devices.
The mechanical devices which actually lock up a telephone set are cumbersome and easily defeated. The mechanical devices can be easily defeated by using portable TOUCH-TONE (R) pads, or even portable telephone sets, see, for example, the device disclosed in U.S. Pat. No. 4,096,357. The use of portable sets is especially important if the locked telephone set is a modular type set. Accordingly, the mechanical telephone locks are not widely accepted.
The term TOUCH-TONE is a registered trademark, and will be capitalized to denote such; however, the notation (R) will be deleted for the sake of brevity. It is noted here that the terms "dial" or "dialing" as used herein in conjunction with a telephone set being operated as a pushbutton-type set means operation of pushbuttons and is not to be confused with rotary dial-type telephone sets.
There are other devices available for preventing coin fraud, wherein only real coins can be used to operate a pay telephone, and other coins, such as slugs, or the like, will not be effective to allow use of such pay telephones. Examples of such fraud preventing devices are disclosed in U.S. Pat. Nos. 4,031,325 and 4,046,962.
Therefore, there is need for a device which prevents unauthorized use of a telephone set which is being operated as a pushbutton-type set, which device is simple to install and can be easily used and altered by a user.